The Japanese Government, which is trying to get the moratorium on commercial whaling lifted at the next meeting of the International Whaling Commission later this month, describes Paul Watson as a "dangerous maverick".

Mr Watson, a Canadian, was one of the founding members of Greenpeace in 1971 and took part in many of its high profile campaigns against whaling and nuclear testing.

But he left in 1977 because his confrontational methods - he proposed ramming illegal whalers - ran counter to the group's policy of non-violence.

Violent confrontations

He set up the Sea Shepherd Conservation Society, bought a new ship and took to the seas again.

In the last 25 years he has had a series of violent confrontations with seal hunters, illegal whalers and various navies during which he has been shot at, chased and arrested.

Sea Shepherd, which is based in Malibu, California, also has a number of celebrity supporters, including actors Martin Sheen, Rutger Hauer, Linda Blair and Pierce Brosnan.

Pierce Brosnan, a friend of Mr Watson's, is among Ocean Warrior's cast

Sheen and Brosnan have both agreed to roles in the film called Ocean Warrior, but the main part is set to go to Aidan Quinn.

Sheen, who has agreed to play a role in Ocean Warrior, described Mr Watson as "by far the most knowledgeable, dedicated and courageous environmentalist alive today".

Tackling illegal fishing

When BBC News Online spoke to him he was tackling a group of illegal shark fishermen off the coast of Guatemala.

His ship, the Ocean Warrior, was engaged in a game of cat-and-mouse with a Costa Rican ship which Mr Watson said was fishing illegally.

Ironically, Mr Watson was en route to Costa Rica to sign a deal with the government which would have protected fish off Cocos Island.

Paul Watson is by far the most knowledgeable, dedicated and courageous environmentalist alive today.

Martin Sheen, actor and supporter

Mr Watson's life would make a dramatic film and Canadian film producer, Pete Kroonenburg, is in the process of doing just that.

Pre-production work began last year with actors signed, ships bought and even model whales made, but funding fell through.

But Mr Kroonenburg said he was confident that they could find a new financier in time for filming to start in Nova Scotia in August.

He said the film would focus on the period shortly after Watson left Greenpeace.

'Terrific script'

Mr Kroonenburg told BBC News Online: "The script is terrific. We have altered the chronology slightly just to make it more dramatic, but it's all based on fact."

He said the film would portray Mr Watson as a "man of action" who takes on those who exploit the oceans.

A minke whale is hauled aboard a Norwegian ship

But Mr Watson's enemies are not just the Japanese and Norwegian Governments, and other whaling supporters.

Nyles Bauer, a former Sea Shepherd crew member, told BBC News Online Mr Watson was "egotistical and vain" and had jeopardised the safety of his crew on occasion.

Mr Watson has also fallen out with Greenpeace.

Speaking by satellite phone from his ship, he told BBC News Online that he felt like Dr Frankenstein for creating Greenpeace.

'Self-perpetuating'

He said: "It has lost its spirit. It now only exists to perpetuate itself. It's a bureaucracy, a business, a brand name for environmentalists."

Mr Watson described Greenpeace as a "bunch of ocean posers" who only turned up at events to get their photographs taken and rarely did anything to stop illegal whaling.

Sea Shepherd II took part in campaigns to protect seal cubs

Greenpeace International raises about $200m a year, compared to the $700,000 which sustains Sea Shepherd.

But Mr Watson said Greenpeace has become a bloated and complacent organisation, which spent $50m on promoting itself and had recently spent millions of dollars on a new headquarters for Greenpeace Germany.

Greenpeace International spokeswoman Sarah Holden said: "We have better things to do than talk about Paul Watson.

"He was part of Greenpeace for a long time, but he is not any more."

If not ramming a boat makes us ocean posers then I'm happy to be an ocean poser. We are non-violent but effective.

Sarah Holden, Greenpeace

She said of the German building: "When you have an organisation as big as ours you need an infrastructure to support that.

"We can't operate without ships, equipment and buildings.

"All of the money we spend is accounted for in our annual report, which is posted on our website, and if people are not happy they will take their subscriptions elsewhere."

Aidan Quinn is set to play the role of Paul Watson

Ms Holden said Greenpeace had never advocated a violent approach to whaling and added: "If not ramming a boat makes us ocean posers then I'm happy to be an ocean poser. We are non-violent but effective."

She said Greenpeace had organised several global days of action to highlight what it claimed were Japanese attempts to buy votes in order to get the moratorium lifted.

'Cultural differences'

A Japanese Government spokesman told BBC News Online: "Unlike the Western nations, Japan has only ever taken whales to eat.

"The West may find eating whales abhorrent, just as many people in India find eating cows abhorrent, but you don't see India trying to blockade the US just because they eat a lot of steak."

He said Japan believed many species of whales were no longer endangered and could be caught commercially without harm.